Neets Module 14 Assignment 3
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What material is applied to electronic assemblies to prevent damage from corrosion, moisture, and stress?
What three methods are used to remove protective material?
What chemicals are used to remove protective material?
Solvents or xylene and trichloroethane.
Abrasion, cutting, and peeling are examples of what type of protective material removal?
Why should the coating material be replaced once the required repair has been completed?
To ensure protective characteristics are maintained.
What term is used to identify the procedure of connecting one side of a circuit board with the other?
Name two types of through-hole termination.
Clinched lead, straight-through, and offset pad.
Turret, bifurcated, and hook terminals are used for what type of termination?
When a lead is soldered to a pad without passing through the board, it is known as what type of termination?
When does most printed circuit board damage occur?
During disassembly or repair.
What procedure involves the use of finely braided copper wire to remove solder?
What is the most effective method of solder removal?
When, if at all, should the heat-and-shake or the heat-and-pull methods of solder removal be used?
These methods should not be used.
To what standards should a technician restore electronic assemblies?
How is oxide removed from pads and component leads?
A fine abrasive.
Leads are formed approximately how many degrees from their major axis?
When you replace components, identification marks must meet what requirements?
They should be readable from a single point.
In what direction are component leads clinched on single- and double-sided boards?
In the direction of the run.
What is solderability?
The ease with which molten solder wets the surfaces of the metals to be joined.
What is the most common source of heat in electronic soldering?
Conductive-type soldering iron.
What determines the shape and size of a soldering iron tip?
The type of work to be done.
What term describes a device used to conduct heat away from a component?
A thermal shunt.
What is the appearance of a properly soldered joint?
Bright and shiny with no cracks or pits.
When removing the component, under what circumstances may component leads be clipped?
If the component is known to be defective or if the board may be damaged by normal desoldering.
How are imbedded TOs removed once the leads are free?
By pushing it gently out of the board.
How is a flat pack removed from a pcb?
Heat each lead and lift with tweezers.
How do you prevent excessive heat buildup on an area of a board when soldering multilead components?
Use a skipping pattern.
What are the two final steps of any repair?
Inspect and test.
List three causes of damage to printed circuit boards.
- Operational failures
- Repairs by untrained personnel
- Repair using improper tools
- Improper shipping
What is the preferred method of repairing cracked runs on boards?
Damaged or missing termination pads are replaced using what procedure?
Epoxy a replacement pad to the board, set an eyelet, and solder it.
How is board damage caused by technicians?
Repairs by untrained personnel and technicians using improper tools.
What combination of materials is used to patch or build up damaged areas of boards?
Epoxy and fiberglass powder.
List two causes of damage to ESD-sensitive electronic components.
Esd, improper stowage, and improper handling.
What is the purpose of the wrist ground strap?
To discharge any static charge built up in the body.
What is the cause of most accidents?
Deviation from prescribed safe operating procedures.
What would you like to do?
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